Ecma has developed a series of Standards for services and signalling protocols in narrowband Private Integrated Services Network (PISNs). These Standards define two signalling systems: QSIG and SSIG. QSIG (signalling system for use at the Q reference point in narrowband PISNs) operates at the Q reference point between Private Integrated Services Network Exchanges (PINXs) connected together within a 64 kbit/s-based PISN. SSIG (signalling system for use at the S reference point in narrowband PISNs) operates at the S reference point between a terminal and a PINX. The signalling protocol Standards are complemented by Standards defining, in abstract terms, services supported by these signalling systems.

The Standards concerned fall into three categories:

Basic Standards

These define basic services, signalling protocols in support
of basic services, and signalling protocols to provide generic
support for supplementary services (SSs) and additional network
features (ANFs). SSs and ANFs provide capabilities beyond a
basic call capability.

NOTE:
ECMA-165 (QSIG generic support for SSs and ANFs) allows for
signalling extensions in support of manufacturer-specific (non-standard)
SSs and ANFs. Such extensions are uniquely identified using
anObject Identifier.

With the exception of SSIG Standards, the Standards listed above have been contributed to ISO/IEC JTC 1 as proposed International Standards. For many of these, corresponding International Standards have now been published by ISO/IEC, based on the Ecma work, and in such cases the current editions of the Ecma Standards are in complete alignment.

Ecma work on these Standards has taken place under a Cooperation Agreement with ETSI and has resulted in the publication of corresponding ETSs or ENs, which endorse the ISO/IEC International Standards where these are available.